The dungeons and dragons type gamer who constantly is watching you and your girl and ends up in the backgroud of all your pictures, staring at the camera.
"Why is there a Fat Man in a Weezer Shirt in the background of all of our pictures?!?!"
by BuddyHolly June 26, 2005
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The third wheel, someone who is always sitting there watching everyone else go at it or have a significant other yet themself is all alone
1.) I'm a fat man in a weezer shirt. All of my friends have someone but i'm all alone.

2.) My friends who are going out with each other invited me to the movied tonight, but i said no because I'm tired of being the fat man in a Weezer shirt.
by poop April 23, 2003
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